Final answer:
The speed of muscle contraction does not increase the force generated, unlike factors such as motor unit recruitment, muscle size, and pennation angle which do enhance muscle contraction strength.
Step-by-step explanation:
The factor that does not contribute to the enhancement of muscle contraction strength is B. Acceleration in the speed of contraction. While an increase in motor unit recruitment, muscle size, and pennation angle generally contribute to stronger muscle contractions, the speed of contraction itself does not increase the force generated during a contraction. Rather, the speed of contraction is influenced by the type of muscle fibers and the intensity of the neuronal stimuli regulating the pace at which muscles contract and relax.
Understanding the elements that influence muscle strength requires familiarity with the muscular system. Recruitment of motor units significantly impacts force as more motor units mean more musclemen working in unison to produce a stronger contraction. The cross-sectional area relates to muscle fibers' size, with larger fibers capable of generating more force. Lastly, the angle of pennation in certain muscles affects the number of sarcomeres and, consequently, the force of contraction. However, the rate at which muscle fibers contract and relax, although it can impact how quickly force is developed, does not directly contribute to the maximum force of that contraction.